When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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Tuesday, January 15, 2013

NOAA: 2012 global temperatures 10th highest on record

According to NOAA scientists, the globally-averaged temperature for 2012 marked the 10th warmest year since record keeping began in 1880. It also marked the 36th consecutive year with a global temperature above the 20th century average. The last below-average annual temperature was 1976. Including 2012, all 12 years to date in the 21st century (2001-2012) rank among the 14 warmest in the 133-year period of record. Only one year during the 20th century--1998--was warmer than 2012.

NOAA: 2012 was the 10th warmest year on record. High resolution. (Credit: NOAA Visualization Lab).

Most areas of the world experienced higher-than-average annual temperatures, including most of North and South America, most of Europe and Africa, and western, southern, and far northeastern Asia. Meanwhile, most of Alaska, far western Canada, central Asia, parts of the eastern and equatorial Pacific, southern Atlantic, and parts of the Southern Ocean were notably cooler than average. Additionally, the Arctic experienced a record-breaking ice melt season while the Antarctic ice extent was above average.

This analysis (summary, full report) from NOAA's National Climatic Data Center is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

2012 global temperature highlights

2012 was the 10th warmest year since records began in 1880. The globally-averaged annual combined land and ocean surface temperature was 1.03 °F (0.57 °C) above the 20th century average of 57.0 °F (13.9 °C). The margin of error is +/- 0.14 °F (0.08 °C).

Record to near-record warm land surface temperatures in the Northern Hemisphere from April to September and overall warmer-than-average ocean surface temperatures made the first 11 months of the year the eighth warmest on record. However, extreme cold across much of the Northern Hemisphere land during December helped lower the year-to-date temperature departure from average by 0.04 °F (0.02 °C) compared with the previous month.

The global annual temperature has increased at an average rate of 0.11 °F (0.06 °C) per decade from 1880 to 2012 and at an average rate of 0.27 °F (0.15 °C) per decade over the past 50 years (1963-2012).

The 2012 worldwide land surface temperature was 1.62 °F (0.90 °C) above the 20th century average, making it the seventh warmest such period on record. The margin of error is +/- 0.32 °F (0.18 °C).

The contiguous United States had its warmest year since national records began in 1895, surpassing the previous record set in 1936 by 1.0 °F (0.6 °C).

Austria experienced its seventh warmest year since national records began in 1767, at 1.8 °F (1.0 °C) above the long-term average.

With the first half of 2012 cooler than average and the second half warmer than average, on balance the annual 2012 temperature across Australia was 0.11 °F (0.06 °C) above the 1961-1990 average. Only the year 2011 has been below average in the past decade.

The 2012 temperature across the United Kingdom was 0.2 °F (0.1 °C) below the 1981-2010 average. This is in part attributed to the UK's coolest summer since 1998 and coolest autumn since 1993.

Norway had its 45th warmest year since record began in 1900, at 0.7 °F (0.4°C) above average.

Weak-to-moderate cold phase La Niña conditions were present in the eastern and central equatorial Pacific Ocean for the first three months of 2012, classifying 2012 as a "La Niña year." ENSO-neutral conditions prevailed for the remainder of the year. The 2012 global combined land and surface temperature was the warmest annual temperature observed during a La Niña year; 2011 was previously the warmest La Niña year on record.

The 2012 global average ocean temperature was 0.81 °F (0.45 °C) above the 20th century average of 60.9 °F (16.1 °C), tying with 2001 as the 10th warmest year on record. It was also the warmest year on record among all La Niña years.

2012 precipitation highlights

Following the two wettest years on record (2010 and 2011), 2012 saw near average precipitation on balance across the globe. However, precipitation varied greatly in some regions.

Major drought gripped important agricultural regions across the world during summer 2012. These regions included eastern Russia, Ukraine, Kazakhstan, and central North America.

By the end of 2012, northeastern Brazil was experiencing its worst drought in decades.

The rainy season was wetter than normal across western and central Africa. Flooding affected more than three million people across 15 countries from July to October.

The United Kingdom had its second wettest year since records began in 1910, falling 7.3 mm shy of the record wetness of 2000. Particularly notable, record dryness during March turned to record wetness in April.

Finland was wetter than average for 2012, with many stations observing their wettest year in the past half century. The capital city of Helsinki reported its second wettest year, behind 1944, since records began in the early 19th century.

2012 snow and polar ice highlights

For all of 2012, Arctic sea ice extent was below average.

On March 18, Arctic sea ice reached its annual maximum extent at 5.88 million square mi (15.24 million square km) -- 0.24 million square mi (0.61 million square km) below average -- which began the annual melt season.

The annual Arctic sea ice melting ended on September 16, when the Arctic sea ice extent dropped to 1.32 million square mi (3.41 million square km), the lowest ever recorded. The annual minimum extent was 49% below average and 0.29 million square mi (0.76 million square km) below the previous smallest extent which occurred in September 2007.

Between March 18 and September 16, 4.57 million square mi (11.83 million square km) of ice melted -- the largest ice loss of any melt season on record. Arctic sea ice during September has been lost at an average rate of 13.0 percent per decade.

Antarctic sea ice extent was above average for most of 2012. Sea ice in the Southern Hemisphere peaked on September 26, reaching its annual maximum extent, at 7.51 million square mi (19.44 million square km). This was the largest Antarctic sea ice extent on record, surpassing the previous record of 7.47 million square mi (19.36 million square km) which occurred in September 2006. Antarctic sea ice during September has increased at an average rate of 0.9% per decade.

Winter (December 2011-February 2012) snow cover extent for the Northern Hemisphere was 228,000 square miles (590,000 square km) above average, making it the 14th largest seasonal snow cover extent on record. North American snow cover was below average during the season, or fourth smallest winter extent on record, while Eurasian snow cover ranked as its fourth largest on record. Spring snow cover extent for the Northern Hemisphere was much below average and ranked as the sixth smallest on record. Both North America and Eurasia had below-average spring snow cover.

The Northern Hemisphere snow cover extent in December 2012 was the largest on record at 1.2 million square mi (3.0 million square km) above average and 0.08 million square mi (0.2 million square km) above the previous record from 1985. Both North America (13th largest) and Eurasia (second largest) had above-average December snow cover.

Winter Northern Hemisphere snow cover has expanded at an approximate rate of 0.1 percent per decade, while spring Northern Hemisphere snow cover has shrunk at an approximate rate of 2.2% per decade.

Global temperature highlights: December

The combined average temperature over global land and ocean surfaces for December was the 18th highest on record for December at 54.74 °F (12.61 °C), or 0.74 °F (0.41 °C), above the 20th century average. The margin of error associated with this temperature is +/- 0.09 °F (0.16 °C).

The global land temperature was 0.38 °F (0.21 °C) above the 20th century average of 38.7 °F (3.7 °C), the 49th warmest December on record and coolest December since 1986.

There was stark contrast between the Northern and Southern Hemisphere land areas during December. Colder-than-average temperatures engulfed most of Eurasia and Alaska, making this the 64th coolest (70th warmest) such December for the Northern Hemisphere on record and the coolest since 1984. Meanwhile, the Southern Hemisphere observed record warm temperatures over land during the month. The land mass in the Southern Hemisphere is much smaller than that of the Northern Hemisphere.

For the ocean, the December global sea surface temperature was 0.85 °F (0.47 °C), above the 20th century average of 60.4 °F (15.7 °C), the sixth warmest for December on record.

NOAA and NASA are two keepers of the world's temperature record. To view NASA's 2012 global temperature summary, visit http://www.nasa.gov/topics/earth/features/2012-temps.html. Although analyses by each agency are independently derived, together with other records maintained by other countries, validate the long-term global record. These analyses provide government, business and community leaders with critical data and information to make informed decisions.